Micro Electro-Mechanical System (MEMS) switches are electrically actuated mechanical switches. Although MEMS switches have some superior properties compared to solid state switches, they suffer from reliability issues like contact force degradation, stiction and dielectric charging. Also, most reported switches are mono-stable, and continuous application of power is required to keep the switch in the actuated state. In this work, a bistable DC MEMS switch is suggested as a solution to these problems. A bistable switch remains stable in both on and off states and retains the state even in the absence of power. The suggested design is suitable for applications where frequent switching is not required.

Buckled beams and thermal actuators are integrated to realize the switch. The buckled beam is designed with an aim to keep to the actuation force as minimum as possible while offering a contact force higher than 10 μN. A lower actuation force will ensure minimum power consumption by the thermal actuator. Design of the buckled beam is explained in detail where each geometrical parameter is optimized to achieve the goal. The thermal actuator with minimum power consumption is designed for the contact force and displacement requirement of the buckled beam. Switches are fabricated without contact metal using an SOI based process flow with a single mask. On testing, switches offer excellent performance in terms of power consumption and speed compared to similar reported works. The average switching power is measured to be 60 mW, while the average switching delay is 350 μs. The switching speed is comparable with that of mono-stable MEMS switches. The power-delay product of about 20 μJ is the lowest reported so far for thermally actuated bistable MEMS switches. It was found that the switch continues to function consistently even after 5 million cycles. This bistable DC switch can be easily extended to an RF MEMS switch. A reliable energy efficient RF MEMS switch with bistable behavior can be used in high frequency applications like phased arrays, switching and reconfigurable arrays.